Traditionally, accurately drawing straight or curved lines required the use of rulers, compasses, protractors, and/or other guides. U.S. Pat. No. 3,384,964 to Phillips and U.S. Pat. No. 4,451,519 to Irrgeher describe guides having a plurality of grooves with rounded junctures, such that when the guide is placed beneath a paper sheet, the grooves guide a marking instrument to draw a line. Phillips, Irrgeher, and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
U.S. Patent Appl. No. 2008/0241802 to Hachey, et al. (publ. October 2008) describes a clipboard having grooves that can be rotated as desired to guide a user in drawing angled lines. U.S. Patent Appl. No. 2008/0070200 to Hachey, et al. (publ. March 2008) describes sketch paper having grooves that embossed onto the writing paper.
Such grooved devices can be useful to draw lines, but can often fail to keep a marking instrument within the desired groove. This results in crooked or otherwise imperfect lines, and thus limits the usefulness of the guide. Although increasing the height of the raised portions can increase the likelihood that a marking instrument remains within the desired groove, larger raised portions will typically deform paper, causing dimples and other surface aberrations. Paper deformations can be avoided reducing the size of the raised portions, but this also reduces the ability of the raised portions to keep the marking instrument within the desired groove.
It is also known to utilize raised portions to teach children how to write. See, e.g., U.S. Pat. No. 7,118,135 to Tims and U.S. Pat. No. 4,669,986. However, such devices have limited use.
Thus, there is still a need for a sketching device having an improved geometry such that a marking instrument is retained within a desired groove while preventing unwanted paper deformations.